This invention is related to databases and the manner in which information is represented and searched.
Computers are often used to store and maintain databases. Databases can be of many types. One type of database stores data in tabular form. One type of tabular form is the relational database that stores information in tables related to each other. Relational databases are defined by properties that are present in the table. The table holds data records, which conform to the properties that define the table. However, if one record presents a new piece of information a new table structure needs to be defined to hold that one record.
Other types of databases include hierarchical databases and flat-file structures that are similar to a table or a spreadsheet. Another type of database is the so-called object-oriented database. Object-oriented databases are also called “persistent objects.” Persistent objects are defined in classes that have data structure and procedural function and at run time are instantiated to have actual values. The object database can persistently store that object so that it can be retrieved with the same run time state as when it was stored.
The world wide web stores information in resources that can be found through an address such as a uniform resource locator (URL). Initially, most resources on the world wide web were plain text or hypertext mark-up language (HTML) documents. Now there are more dynamic forms of resources available. A resource will use a database to provide information and display it as an HTML document.
A Web crawler is a software program used to search information on the web. A web crawler starts at a page or a set of pages and searches through documents by following links. The links lead from one document to another. The links only contain locational information, i.e., a uniform resource locator (URL) that gives an address or location of the resource, i.e., a server that contains the referenced page.